MU variability in CBCT-guided online adaptive radiation therapy.

Purpose: CBCT-guided online-adaptive radiotherapy (oART) systems have been made possible by using artificial intelligence and automation to substantially reduce treatment planning time during on-couch adaptive sessions. Evaluating plans generated during an adaptive session presents significant challenges to the clinical team as the planning process gets compressed into a shorter window than offline planning. We identified MU variations up to 30% difference between the adaptive plan and the reference plan in several oART sessions that caused the clinical team to question the accuracy of the oART dose calculation.

Using machine learning to predict gamma passing rate in volumetric-modulated arc therapy treatment plans.

Purpose: This study aims to develop an algorithm to predict gamma passing rate (GPR) in the volumetric-modulated arc therapy (VMAT) technique.

Materials And Methods: A total of 118 clinical VMAT plans, including 28 mediastina, 25 head and neck, 40 brains intensity-modulated radiosurgery, and 25 prostate cases, were created in RayStation treatment planning system for Edge and TrueBeam linacs. In-house scripts were developed to compute Modulation indices such as plan-averaged beam area (PA), plan-averaged beam irregularity (PI), total monitor unit (MU), leaf travel/arc length, mean dose rate variation, and mean gantry speed variation.

Evaluation of parameters affecting gamma passing rate in patient-specific QAs for multiple brain lesions IMRS treatments using ray-station treatment planning system.

Purpose: Using intensity-modulated radiosurgery (IMRS) with single isocenter for the treatment of multiple brain lesions has gained acceptance in recent years. One of the challenges of this technique is conducting a patient-specific quality assurance (QA), involving accurate gamma passing rate (GPR) calculations for small and wide spread-out targets. We evaluated effects of parameters such as dose grid and energy on GPR using our clinical IMRS plans.

Technical Note: Influence of Compton currents on profile measurements in small-volume ion chambers.

Purpose: This work is to evaluate the effects of Compton current generation in three small-volume ionization chambers on measured beam characteristics for electron fields.

Methods: Beam scans were performed using Exradin A16, A26, and PTW 31014 microchambers. Scans with varying chamber components shielded were performed.

Correction factor measurements for multiple detectors used in small field dosimetry on the Varian Edge radiosurgery system.

Purpose: Accurate dosimetry of small fields remains a challenge to the clinical physicist. Choosing the appropriate detector and determination of kQclin,Qmsr (fclin,fmsr) factors continue to be an area of active research. The purpose of this study is to evaluate the output factors for a dedicated stereotactic accelerator using multiple dosimeters designed for use in small fields and evaluate published kQclin,Qmsr (fclin,fmsr) factors relative to measured values using a commercial scintillating fiber.